Field of the Invention
The present invention relates generally to electrically operated door locking systems in which the door is unlocked by accessing an electronic control system, and more particularly to an improved door access bar for installation onto a door through which access is controlled by an electrically operated door access system, whereby the door access bar has an electromechanically operable door locking mechanism which is used to selectively lock and unlock the door to thereby control access or egress through the door.
Security doors to prevent theft or vandalism have evolved over the years from simple doors with heavy duty locks to more sophisticated egress and access control devices. Hardware and systems for limiting and controlling egress and access through doors are generally utilized for theft-prevention or to establish a secured area into which (or from which) entry is limited. For example, stores use such secured doors in certain departments (such as, for example, the automotive department) which may not always be manned to prevent thieves from escaping through the door with valuable merchandise. In addition, industrial companies also use such secured exit doors to prevent pilferage of valuable equipment and merchandise.
Such doors and systems have evolved over the years from simple doors having heavy duty mechanical locks thereon to sophisticated egress and access control devices. In bygone times, heavy duty chains and locks were the norm on security doors which were not generally used, or which were used to prevent theft or vandalism. However, fire codes have made such relatively simple door locking systems obsolete, at least in most developed countries. Emergency exit doors are required by law to be provided in all commercial buildings, and such doors must be operative in the event of a fire, earthquake, or other emergency.
These exit doors are typically provided with heavy horizontal push bars, which unlock the door upon actuation and which may provide an alarm of some sort. The early alarms on such doors were either mechanical in nature, such as wind-up alarms contained on the push bar mechanism, or completely separate electrical circuits actuated by a switch opened as the door was opened. Accordingly, egress from such doors was immediate, and, although egress was accompanied by an alarm, typically the person leaving through the door was long gone by the time security personnel arrived.
As might be expected, the art reflects a number of emergency exit access activation devices which attempt to solve this problem. An example of one such device is found in U.S. Pat. No. 4,257,631, to Logan, Jr., which describes a system activated by a push bar which, upon depression, moves a switch carried by the door to sound an alarm and start a timer delay. After the delay, the door is unlocked.
This type of device in which a push bar containing an electrical switch therein is used to initiate a request for access or egress is by far the most common. Several other types of systems have been proposed, and, although none of these systems has found great acceptance, a brief discussion of them is in order.
U.S. Pat. No. 4,328,985 and U.S. Pat. No. 4,354,699, both also to Logan, teach a hydraulic system for accomplishing the delay prior to unlocking the door, and a retrofit locking device of the same type which is usable with any door latching system, respectively. These two systems are thus mechanical rather than electrical in nature.
A door access bar utilizing an electric switch to actuate a discrete electrically operated locking mechanism is illustrated in U.S. Pat. No. 5,564,228, to Geringer et al. The improved door access bar of the Geringer et al. '228 patent contains an electromechanical mechanism through which mechanical contact by a user with the door access bar is translated into an electrical output, which may be utilized to initiate the process of unlocking the door on which the door access bar is mounted. The transducer used by the door access bar of the Geringer et al. '228 patent is a force sensing resistor (FSR), which has a resistance which drops when a compressive force exerted across the force sensing resistor increases.
Despite its disadvantages, the preferred type of door access bar is the mechanically operated door access bar with an electrical switch incorporated therein to control an integral locking mechanism. Accordingly, it is the primary objective of the present invention that it present an improved door access bar having an electromechanical locking mechanism incorporated therein to selectively lock and unlock a door on which the door access locking bar is mounted to thereby control access or egress through the door. It is a related objective that the locking mechanism will positively prevent the door from being opened until the electromechanical locking mechanism is operated to do so, it is another primary objective of the door access locking bar of the present invention that the locking mechanism be integrated into the design of the door access locking bar, and that the locking mechanism not be visible from the exterior of the door access locking bar.
It is a closely related objective of the door access locking bar of the present invention that the switch which indicates that access or egress is desired be triggered by pressure on the door access locking bar. It is a further objective of the door access locking bar of the present invention that despite the incorporation of these aspects it present a low-profile design similar to that of a conventional door access bar. It is still another primary objective of the door access locking bar of the present invention that its mechanical design incorporate an interlock mechanism to positively prevent the bolt from being forced into a retracted position by jimmying the locking mechanism to unlock the door.
It is a further objective that the door access locking bar of the present invention operate in a fail-safe manner such that, in the event of a power failure, the door access locking bar will automatically be placed into an unlocked position. It is an additional objective of the door access locking bar of the present invention that it allow the bolt to retract as the door is closed without first requiring the unlocking mechanism to be actuated. It is a still further objective of the door access locking bar of the present invention that it be of a robust design so as to not require frequent adjustment of mechanical tolerances within the device, and that it be both easy and quick to mount on any door or other desired location.
The door access locking bar of the present invention must be of a construction which is both durable and long lasting, and it should also require little or no maintenance to be provided by the user throughout its operating lifetime. In order to enhance the market appeal of the door access locking bar of the present invention, it should also be of inexpensive construction to thereby afford it the broadest possible market. Finally, it is also an objective that all of the aforesaid advantages and objectives of the apparatus of the door access locking bar of the present invention be achieved without incurring any substantial relative disadvantage.